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Overexpression of the ATPase Inhibitory Factor 1 Favors a Non-metastatic Phenotype in Breast Cancer

View Article: PubMed Central - PubMed

ABSTRACT

Partial suppression of mitochondrial oxidative phosphorylation and the concurrent activation of aerobic glycolysis is a hallmark of proliferating cancer cells. Overexpression of the ATPase inhibitory factor 1 (IF1), an in vivo inhibitor of the mitochondrial ATP synthase, is observed in most prevalent human carcinomas favoring metabolic rewiring to an enhanced glycolysis and cancer progression. Consistently, a high expression of IF1 in hepatocarcinomas and in carcinomas of the lung, bladder, and stomach and in gliomas is a biomarker of bad patient prognosis. In contrast to these findings, we have previously reported that a high expression level of IF1 in breast carcinomas is indicative of less chance to develop metastatic disease. This finding is especially relevant in the bad prognosis group of patients bearing triple-negative breast carcinomas. To investigate the molecular mechanisms that underlie the differential behavior of IF1 in breast cancer progression, we have developed the triple-negative BT549 breast cancer cell line that overexpresses IF1 stably. When compared to controls, IF1-cells partially shut down respiration and enhance aerobic glycolysis. Transcriptomic analysis suggested that migration and invasion were specifically inhibited in IF1-overexpressing breast cancer cells. Analysis of gene expression by qPCR and western blotting indicate that IF1 overexpression supports the maintenance of components of the extracellular matrix (ECM) and E-cadherin concurrently with the downregulation of components and signaling pathways involved in epithelial to mesenchymal transition. The overexpression of IF1 in breast cancer cells has no effect in the rates of cellular proliferation and in the cell death response to staurosporine and hydrogen peroxide. However, the overexpression of IF1 significantly diminishes the ability of the cells to grow in soft agar and to migrate and invade when compared to control cells. Overall, the results indicate that IF1 overexpression despite favoring a metabolic phenotype prone to cancer progression in the specific case of breast cancer cells also promotes the maintenance of the ECM impeding metastatic disease. These findings hence provide a mechanistic explanation to the better prognosis of breast cancer patients bearing tumors with high expression level of IF1.

No MeSH data available.


Related in: MedlinePlus

Breast cancer inhibitory factor 1 (IF1)-overexpressing (gray line and bars) cells are more vulnerable and migrate and invade less than control (CRL, black and closed bars) breast cancer cells. (A) Cellular proliferation at 24, 48, and 72 h. (B) Cell death after 24 h of priming the cells with 1 μM staurosporine (STS) or 120 μM hydrogen peroxide. *p < 0.01 when compared to non-treated by Student’s t-test. (C) Representative images of the anchorage-independent growth in soft agar. (D) Representative time frames of the wound healing video assays. (E) Representative images of the matrigel invasion assays at 48 and 72 h. The histograms (C,D) and graph (E) show the quantification as the means ± SEM; *p ≤ 0.05 when compared to CRL by Student’s t-test.
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Figure 5: Breast cancer inhibitory factor 1 (IF1)-overexpressing (gray line and bars) cells are more vulnerable and migrate and invade less than control (CRL, black and closed bars) breast cancer cells. (A) Cellular proliferation at 24, 48, and 72 h. (B) Cell death after 24 h of priming the cells with 1 μM staurosporine (STS) or 120 μM hydrogen peroxide. *p < 0.01 when compared to non-treated by Student’s t-test. (C) Representative images of the anchorage-independent growth in soft agar. (D) Representative time frames of the wound healing video assays. (E) Representative images of the matrigel invasion assays at 48 and 72 h. The histograms (C,D) and graph (E) show the quantification as the means ± SEM; *p ≤ 0.05 when compared to CRL by Student’s t-test.

Mentions: Assessment of the rates of cellular proliferation (Figure 5A) and of cell death after hydrogen peroxide or STS treatment (Figure 5B) revealed no relevant differences between control and IF1-expressing cells. Interestingly, soft agar colony-formation assays showed that IF1-cells had a significant less capacity to grow and form colonies in the anchorage-independent assay (Figure 5C), suggesting a lower tumorigenic potential. To verify the migration ability of the cells, wound healing assays were carried out (Figure 5D). The results revealed that control cells started filling and fully occupied the scratched area earlier than IF1-cells (Figure 5D; see Video S1 in Supplementary Material), indicating that IF1-overexpressing cells had less migration ability than control cells. Similarly, matrigel invasion assays also revealed that control cells had a higher invasive capacity than IF1-cells (Figure 5E). Overall, these results suggest that IF1 overexpression in breast cancer cells induces a less aggressive phenotype by diminishing the migration and invasive capacities of the cells. This finding agrees with the fact that breast cancer patients with elevated tumor levels of IF1 had less metastatic disease.


Overexpression of the ATPase Inhibitory Factor 1 Favors a Non-metastatic Phenotype in Breast Cancer
Breast cancer inhibitory factor 1 (IF1)-overexpressing (gray line and bars) cells are more vulnerable and migrate and invade less than control (CRL, black and closed bars) breast cancer cells. (A) Cellular proliferation at 24, 48, and 72 h. (B) Cell death after 24 h of priming the cells with 1 μM staurosporine (STS) or 120 μM hydrogen peroxide. *p < 0.01 when compared to non-treated by Student’s t-test. (C) Representative images of the anchorage-independent growth in soft agar. (D) Representative time frames of the wound healing video assays. (E) Representative images of the matrigel invasion assays at 48 and 72 h. The histograms (C,D) and graph (E) show the quantification as the means ± SEM; *p ≤ 0.05 when compared to CRL by Student’s t-test.
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Figure 5: Breast cancer inhibitory factor 1 (IF1)-overexpressing (gray line and bars) cells are more vulnerable and migrate and invade less than control (CRL, black and closed bars) breast cancer cells. (A) Cellular proliferation at 24, 48, and 72 h. (B) Cell death after 24 h of priming the cells with 1 μM staurosporine (STS) or 120 μM hydrogen peroxide. *p < 0.01 when compared to non-treated by Student’s t-test. (C) Representative images of the anchorage-independent growth in soft agar. (D) Representative time frames of the wound healing video assays. (E) Representative images of the matrigel invasion assays at 48 and 72 h. The histograms (C,D) and graph (E) show the quantification as the means ± SEM; *p ≤ 0.05 when compared to CRL by Student’s t-test.
Mentions: Assessment of the rates of cellular proliferation (Figure 5A) and of cell death after hydrogen peroxide or STS treatment (Figure 5B) revealed no relevant differences between control and IF1-expressing cells. Interestingly, soft agar colony-formation assays showed that IF1-cells had a significant less capacity to grow and form colonies in the anchorage-independent assay (Figure 5C), suggesting a lower tumorigenic potential. To verify the migration ability of the cells, wound healing assays were carried out (Figure 5D). The results revealed that control cells started filling and fully occupied the scratched area earlier than IF1-cells (Figure 5D; see Video S1 in Supplementary Material), indicating that IF1-overexpressing cells had less migration ability than control cells. Similarly, matrigel invasion assays also revealed that control cells had a higher invasive capacity than IF1-cells (Figure 5E). Overall, these results suggest that IF1 overexpression in breast cancer cells induces a less aggressive phenotype by diminishing the migration and invasive capacities of the cells. This finding agrees with the fact that breast cancer patients with elevated tumor levels of IF1 had less metastatic disease.

View Article: PubMed Central - PubMed

ABSTRACT

Partial suppression of mitochondrial oxidative phosphorylation and the concurrent activation of aerobic glycolysis is a hallmark of proliferating cancer cells. Overexpression of the ATPase inhibitory factor 1 (IF1), an in vivo inhibitor of the mitochondrial ATP synthase, is observed in most prevalent human carcinomas favoring metabolic rewiring to an enhanced glycolysis and cancer progression. Consistently, a high expression of IF1 in hepatocarcinomas and in carcinomas of the lung, bladder, and stomach and in gliomas is a biomarker of bad patient prognosis. In contrast to these findings, we have previously reported that a high expression level of IF1 in breast carcinomas is indicative of less chance to develop metastatic disease. This finding is especially relevant in the bad prognosis group of patients bearing triple-negative breast carcinomas. To investigate the molecular mechanisms that underlie the differential behavior of IF1 in breast cancer progression, we have developed the triple-negative BT549 breast cancer cell line that overexpresses IF1 stably. When compared to controls, IF1-cells partially shut down respiration and enhance aerobic glycolysis. Transcriptomic analysis suggested that migration and invasion were specifically inhibited in IF1-overexpressing breast cancer cells. Analysis of gene expression by qPCR and western blotting indicate that IF1 overexpression supports the maintenance of components of the extracellular matrix (ECM) and E-cadherin concurrently with the downregulation of components and signaling pathways involved in epithelial to mesenchymal transition. The overexpression of IF1 in breast cancer cells has no effect in the rates of cellular proliferation and in the cell death response to staurosporine and hydrogen peroxide. However, the overexpression of IF1 significantly diminishes the ability of the cells to grow in soft agar and to migrate and invade when compared to control cells. Overall, the results indicate that IF1 overexpression despite favoring a metabolic phenotype prone to cancer progression in the specific case of breast cancer cells also promotes the maintenance of the ECM impeding metastatic disease. These findings hence provide a mechanistic explanation to the better prognosis of breast cancer patients bearing tumors with high expression level of IF1.

No MeSH data available.


Related in: MedlinePlus